Dear Maurizio,
Thanks for the compliments!
The Harley Davidson FXR gastank is an almost perfect fit, there are only two modifications needed; you have to take a part out of the mounting brackets, because the original ones are too broad, and you have to cut new holes in the rear tank-mount and saw off some steel, because this part is too long, but it's not too much work. Your two-part-tank will probably be almost as much work, you just have to fix new brackets, which isn't too much work, you only need the correct tools.
I think this is the kind of tank you're talking about, and it shouldn't be too hard to fix it to your Savage. This set is really interesting!
I won't be using the tacho and speedo, I'll just use a digital bicycle-speedo. As you see, there will be a gap on the tank where the speedo and tacho were, but I'm getting a big leather tankpad fixed, which runs all the way from the bottom to the top of the tank to cover the hole. To make sure thise doesn't collapse I'll have some aluminium sewn in on top.
I saw the rear fender on marktplaats.nl, the dutch ebay.com. There is another fender for sale on this site right now, the yellow one. If you'd like to buy it, please send me an email and I'll give you this guys emailadress.
Good luck and please show us some pictures once you're done building